In 1984, in the roots of a thorn tree on the shores of Lake Turkana in Kenya, a paleontologist called Kamoya Kimeu found the near complete skeleton of boy who died around 1.5 million years ago.

Turkana Boy, as he came to be known, probably belonged to a species called Homo Ergaster – an early form of human that evolved in Africa some two million years ago, and which is thought to be the direct ancestor of modern humans.

By the time of Turkana Boy, in the early Pleistocene era, the floor of the Wadi Araba and the Jordan Valley had slumped, while the highlands along the edge of the rift were being raised and tilted into the mountains we see today. These geological forces reconfigured the patterns of the watershed, draining the winter rains into the Rift Valley and creating freshwater lakes from the southern deserts of the Wadi Araba to the highlands of the Golan.

THE FIRST HUMANS IN THE VALLEY

In the heat and humidity of the valley, trees and grasslands flourished, drawing great herds of animals from the African savannah. Embedded in the mud of the Jordan Valley are the fossilized remains of crocodile and hippopotamus, gazelle and warthog, rhinoceros and leopard.

Perhaps as long as 1.8 million years ago, small bands of early humans began to appear in this landscape. They were omnivorous scavengers, feeding on carcasses killed by other large predators, and its possible that they found their way here by following the animals out of east Africa. However they arrived, they were the first humans ever to leave the African continent.

UBEIDIYA

It’s highly likely that these people drank from the springs of Jericho and Auja, but the first hard evidence of their presence in the valley comes from a few kilometers further north. At the site of Ubeidiya, on the shores of a lake that vanished in prehistory, archaeologists have found fragments of cranial bone and teeth, more than a million years old, that almost certainly came from the same species as Turkana Boy. Who were these people, and how different were they from us?

From the more complete skeletons found in Africa, paleontologists have been able to reconstruct Homo Ergastus in some detail. Turkana Boy, who died at around 10 years old, was already 1.6m in height, which suggests that the adults of the species may have been as tall as modern humans. Their bodies were hairless, and dark skinned, and muscled for running and hunting. Their had elongated faces and pronounced brow lines. They could probably talk in something recognizably like a human voice, though their range of vocalization and the complexity of their language was nothing like modern human speech, and their brains were far smaller than our own.

Along with fragments of their skulls, the men and women who camped on the muddy lakeshore at Ubeidiya left behind distinctive stone hand axes, shaped like a teardrop and flaked to an edge along both sides. The Ubeidiya axes are probably around 1.4 million years old, and appear to have been part of a standardized tool-making tradition that appeared in Africa at around that time. They were used to hack meat from the bones of animals, to break the bones and extract the marrow, and to cut and scrape animal skins. It’s possible that the people who made these axes also knew how to control fire, and perhaps even to cook food.

The early humans who walked through the valley eventually went deep into Europe and Asia. But they did not survive, and they are not our direct ancestors. Around 100,000 or 150,000 years ago, long after Homo Ergastus had vanished, a new species of human followed their footsteps out of Africa and found their way into the rift north of Jericho. By about 25,000 years ago, some of the people – anatomically modern humans – had abandoned nomadism entirely, and had settled to hunt and fish and forage in the fertility of the Jordan valley.